Method and apparatus for producing motor fuel



July 11, 1939, P. A. MAscHwlTz f METHOD AND APPARATUS FOR PRODUCING MOTOR` FUEL Filed Aug. 15, 1936 2 Sheets-Sheet 1 miv P. A. MASCHWITZ METHOD AND APPARATUS FOR PRODUCING MOTOR FUEL July 11, 1939.

Flled Aug. 13, 1936 Patented July 11, 1939 UNITED STATES PATENT OFFICE METHOD AND APPARATUS 'FOR PRODUCING MOTOR FUEL tion of Ohio Application August 13, 1936, Serial No. 95,745

` 1 2 claims.

This invention relates to method and tapparatus for producing high yields of high octane motor fuel from crude oil. More particularly the invention resides in the combination of cracking,

5 reforming`,'and polymerizing in such manner that crude oil may be subjected to a continuous process in which the cracking stock, naphthavand gases are treated simultaneously in a unitary process to convert them into motor fuel. In accordance with the invention, crude oil may be topped in the usual manner to remove the gasoline, naphtha, and/or kerosene. The total overhead cut maybe reformed at elevated temperatures and pressures or only the heavier fraction thereof may be reformed. 'I'he topped crude may be subjected to any suitable cracking operation in liquid, liquidvapor, or vapor phase, and the resulting gasolinedistillate combined with the products from the. reforming operation. :0 The combined products maybe clay-treatedand fractionated to end point gasoline. The heavy ends separated from the mixture may be recycled to the cracking unit.

The gases from the cracking and reforming 5 operation may be intimately contacted with a portion or all the overhead fraction to be reformed under elevated pressure in order to dissolve a portion. of the gases. The naphtha'enriched with the heavier gas fractions may be m subjected to reforming, and the unabsorbed gases may be subjected to suitable conversion in a separate still. The distillate produced in the gas conversion step may be combined with the cracked distillate and the reformed naphtha. The gas resulting from the gas conversion may be fractionated by absorption to remove hydrogen, methane and other light gases, and the absorbed constituents separated from the absorbent and recycled to the gas conversion zone. A composite distillate of cracked gasoline, reformed naphtha, and polymerized condensate is formed having an unusually high octane rating. 'I'he yield of gasoline is also higher than has heretofore been obtained for 'gasoline of equivalent knock rating.

The invention may be more clearly understood from the following detailed description considered in connection with the accompanying drawings, of which,

so Figure l is 'a diagrammatic elevational view of apparatus forming part of the invention and in which the method may be carried out.

Figure 2 is a diagrammatic View of conventional apparatus for topping and cracking crude cill- (ci. 19e- 9) Referring to the drawings, naphtha, gasoline, or kerosene may be charged through line I by means of pump 3 either directly into the heating and reforming coil 5 located in furnace 6, or through the line 1 controlled by valve 9. The naphtha, etc. may be obtained directly from a topping unit used in conjunction with the oil crackingprocess, or may be obtained from a sep; arate source. If desired, the charging stock may be split into two streams by proper regulation of the valve 9 in line 1 and the valve I I in line I. From the line I the charging stock, which is preferably heavy naphtha, passes into the top of an absorption tower I3 where it passes in countercurrent contact with a stream of gases fed to the lower portion of the absorber through the line I5. The gases fed through line I5 may contain unsaturated hydrocarbons ranging in amount from -55%. The absorption tower is preferably operated at a pressure of from 15G-200 pounds per square inch and at a temperature of 100 F. or less.

Rich oil is withdrawn from the bottom of the absorption tower I3 through line I1 by means of pump I9 and is charged through line I into the heating and reforming coil 5. The oil thus charged to the coil 5 will have dissolved therein the heavier constituents of the gas, such as butane, butylene and some propane and propylene. The rich oil may be subjected to pressures of 500-3000 pounds per square inch and to tempera tures ranging from 800-1200 F. in the coil 5.

The products leaving the reforming coil 5 pass into arrester 2l where they are contacted with cool oil withdrawn from the gas separator 23 through line 25 by means of pump 21. The reaction products are chilled in the arrester 2l to a temperature below 700 F. and. preferably to a temperature between 500 and 600 F. The 'partially cooled reaction products pass through line 29 controlled by valve 30`to the upper portion of a chamber 3| containing a bed of fullers earth or other clay capable of functioning as an adsorptive catalyst. The clay chamber may be` maintained under substantially reaction pressure or the pressure may be reduced somewhat by means of the valve 30 before the products enter the clay chamber. In the clay chamber the unstable gum-forming and color-imparting bodies undergo polymerization to heavier bodies. The combined reaction products are withdrawn from the bottom of the clay chamber through line t0 controlled by valve and pass into the lower portion of fractionating tower 31. The pressure on the products may be reduced to approximately 150-200 pounds per square inch or lower before entering the fractionating tower. Ii' necessary, the products leaving the clay chamber may be preheated prior to passing into the fractionating tower. In the fractionating tower 31, vaporization of the lighter vapors boiling within the gasoline range takes place, and these vapors pass overhead through line 33 while the heavier ends and polymers formed in the clay chamber and in the reforming coil 5, may be withdrawn through the line 4| controlled by valve 43. Open steam may be used in tower 31 and in subsequent vfractionating towers to assist in separating light ends from the unvaporized portions. When open steam is used, suitable provision should be made vfor drawing olf water from the separators following the fractionating towers. The higher boiling materials withdrawn through line 4| may be recycled to an Ioil cracking unit, such as a vapor phase unit, or may be withdrawn from the system. It is apparent that the heavy boiling liquid withdrawn through the line 4| may be in part withdrawn from the system and in part recycled to an oil cracking system.

The vapors and gases withdrawn through line 39 pass through the condenser 45 where the temperature of the products is lowered to approximately 100 F. or less and then through line 41 into accumulator 43. -The condensate collected in accumulator 43 may be in part withdrawn through line 5| by lmeans of pump 53 and recycled to the upper portion of the fractionating tower 31 as reiiux. 'I'he remaining portion of the condensate may be withdrawn from the bottom of the accumulator 43 through line 55 Vcontrolled by valve 51, into accumulator 53.

Uncondensed gases leave the top of the accumulator 49 through line 6|, pass through cooler 03 where the temperature is further reduced, if necessary, to or below 100 F., and are then charged through line 61 into accumulator 53. Gas

leaving the top of gas separator 23 through line 1| may be compressed by compressor 13 to a pressure of approximately 150-200 pounds per square inch and charged into accumulator 53 together with the gases from accumulator 43. The gases from the gas separator 23 may result from the cracking oi' topped crude or other oil in Aa. cracking process, of the liquid, liquid-vapor, or vapor phase type. 'I'he combined gases and' gasoline distillate from the cracking unit may' pass through line 15, after having been cooled to a temperature suilicient to condense the vapors boiling within the gasoline range, into the gas separator 23 where the gas separates from the condensate.

Uncondensed' gases leave the top of the accumulator 59 through line 11 and, after being cooled if necessary by passing through a cooler (not shown), pass into the lower portion of the absorber I3 through the line I5. Any liquids condensed in accumulator 5I may be withdrawn therefrom through line 19 by means of pump 3| and charged intothe upper portion of a stabilizer 33. The stabilizer is preferably maintained under a pressure of from 175-225 pounds per square inch. The stabilizer is equipped with bubble plates in order tosecure fractionation. `Unvaporized products may be withdrawn from the lower portion of the stabilizer through line I5 and passed into lreboiler 81 where they are heated to a temperature suiilcient to vaporize those constituents such as propylene, butylene. propane and butane, which are undesirable in gasoline. These A vapors and gases return from the reboiler to the stabilizer through line 89. 'Ihe unvaporiz'ed portions are withdrawn from the reboiler through line 0| and may be charged to the storage tank 92 through line 93 controlled by valve 94, or may be withdrawn to separate storage through line 91 controlled by valve 93. Uncondensed gases leave the stabilizer '33 through line |0I, pass through condenser |03 into accumulator |05. Any condensate which forms in the accumulator may be recycled through line |01 by means of pump |09 to the top of the stabilizer, as reux. 'I'he uncondensed gases leave the top of the accumulator |35 through line pass through cooler H3, where the temperature is reduced to 100 F. or less, and join the gases from line 11 passing into the absorber |3.

Unabsorbed gases leave the top of the absorber I3 through line H5 and are charged by means of compressor ||1 to the heating coil ||9 located in furnace |2|. The gases may be heated to a temperature ranging from 800-1400 F. in the coil ||3 under pressures oi' from 100-3000 pounds per square inch. The pressure used will depend upon the temperature to which the gases are heated. At higher temperatures, the pressure Will be correspondingly lower, while at lower temperatures, higher pressures will be used. The temperature to which the gases are heated will depend to a large extent on the olefinic content of the gases. With gases of less than about 30% olefinic content, it is preferable to use temperatures of 1200 1400" F. in order to obtain substantial cracking together with polymerization. When the olenic content oi' the gases exceeds approximately 30%, temperatures below 1200 F. are preferable. 'I'he heated gases leave coil ||9 through line |23 controlled by valve |25 and may be either passed through reaction zone |21 or may be by-passed around the reaction zone through line |29 controlled by valve |3|. The reaction zone |21 may take either the form of an enlarged coil or an enlarged reaction chamber preferably heat insulated. If the products are subjected to high pressure treatment, it may be desirable to use the reaction zone, but Where high temperatures and low pressures are used with consequent short reaction periods, it may be desirable to by-pass the reaction zone. 'I'he particular conditions of temperature and pressure and the period of reaction desired will determine whether or not the reaction zone will be utilized. The products leaving the reaction zone |21 or the heating coil H9, as the case may be, pass through line |33 controlled by valve |35 into the lower portion of evaporator |31. Immediately after leaving the reaction zone or the heating coil, the products are quickly chilled to a temperature of 600 F. or lower by means of contact with cool oil withdrawn from gas separator |33 through line |4| by means of pump |43. A portion of the oil from the line |4| may be charged into the upper portion'of the evaporator |31 through line |45 controlled by valve |41 to act as reflux. The pressure of the products en tering the evaporator is preferably reduced to approximately 175-225 pounds per square inch. Tarry constituents are knocked out and Withdrawn from the bottom of the evaporator through line |43 controlled by valve |5| and may be either recycled to the oil cracking step o1` withdrawn from the system. The remaining vapors and gases pass over the top of the evaporator through line |53, condenser |55 and line |51, into accumulator |53.

Condensate may be Withdrawn from the ac- 0101111131201 |59 through line |6| and charged to the gas separator |39. Uncondensed gases from the accumulator |59 are Withdrawn from the top thereof through line |62 controlled by valve |63 and may be charged through line IBN controlled by valve |65 to the lower portion of absorption tower |61. When the gas conversion system is operated. under low pressure, it may be necessary to compress the gases leaving accumulator |59, by means of compressor |68, prior to delivery to the absorber. Absorption oil, which may be heavy naphtha, mineral seal or gas oil, may be charged int/o the upper portion of the absorber through line |69 and passed in countercurrent contact with the gases charged to the absorber through line |6tl. 'I'he unabsorbed gases leave the top of the absorber through line Hl controlled by valve |13 and may be withdrawn from the system. The rich absorber oil may be withdrawn from the bottom of the absorber through line Wb, passed through heat exchanger i'i'l, line |19 controlled by valve wd and heater itil, into an intermediate portion of the still Miti. The absorbed gases and light vapors are stripped from the absorber oil and pass ofi the top of the still through line wb, through condenser itil, into the gas separator it@ where the condensed vapors mix with the condensate from the accumulator ibid. A part of the condensate from the separator .i3d may be returned from the bottom thereof through line it@ by means of pump iti to the top of the still ttm, as reilux. As previously stated, a portion of this condensate may be used as chilling fluid for the products leaving the polymerization zone. The remaining condensate is withdrawn from separator i3d through line |93 and may either be charged by means of pump ld to the gas separator 2t lwhere it is combined with the cracked light distillate to undergo clay treatment and ilnai fractionation, or may be Withdrawn from the system through line |95 controlled by valve Idil and separately collected. Uncondensed gas may be taken off the top of separator |39 and recycled to the inlet oi coil H9 through line ist.

The denuded absorber oil is withdrawn from the bottom of the still iti by means of pump litt through line Wil, heat exchanger ill, where it gives up a portion oi its heat to the rich oil, and then charged through line it@ and cooler 2M into the top of the absorber. Makeup oil may be added to the line l t9 as required through line 203 controlled by valve Ebb. The absorber itl is preferably maintained under a pressure oi 175-225 pounds per square inch and at a tem-v perature of approximately 100 F. or less. The

still M33 and gas separator it@ are preferably maintained under pressure of 15G-206 pounds per squarev inch, but may be maintained at lower pressures when polymerization is carried out at low pressures.

lt will be apparent that instead of utilizing separate absorption and stripping means for the uncondensed gases from the accumulator itil, the uncondensed gases therefrom may be recycled .v in whole or in part to the absorber i3 through line 2M controlled by valve ttt. In order to do this it merely is necessary to close valves itt in line itt and to open the valve M9 in line 2M. When operating in this manner excess gas may be removed from the system throughline till controlled by valve 2li.

Referring to Figure 2, crude oil is pumped by means of pump 220 through line 222 into heating coil 22d. In the coil 22d the oil is heated sumclently to vaporize the oil but not to crack it.

From the heating coil the oil passes into the fractionating tower 226. Gasoline is withdrawn overhead as a vapor through line 228 and passed through condenser 23|! into separator 232 from which it may be withdrawn through line 231i controlled by valve 236i.

Heavy naphtha containing or not containing kerosene may be withdrawn from an intermediate portion of the fractionator 226 through line 23B. Line 23d is connected to line 238 by line 24W controlled by valve 242 so that topped gasoline may be mixed with heavy naphtha if desired prior to charging the latter through line to the reforming coil.

Cracking stock may be withdrawn from the lower 'portion of the tower through line 241i con trolled by valve 24m and charged by means of pump 248 through heating and cracking coil tt. From the cracking coil the reaction products may pass into evaporator 2h22. The vapors pass overhead from the evaporator through line 25d controlled by valve 2556 into fractionating tower 25B. Gasoline and gases are taken overhead from the iractionating tower through line 2653 controlled' by valve 2M into cooling and condensing coil 26d. From the coil 26d the mixed gases and gasoline pass through line l to separator 23.

From the foregoing description it will be seen that a system has been provided for treating crude oil whereby the oil may be rst topped and the natural gasoline fraction obtained from the topping operation or a heavy fraction thereof reformed either alone or4 in conjunction with conversion ci hydrocarbon gases obtained from the cracking and reforming steps. The system further provides for conversion of the lighter portions of the gases under any desired conditions in order to produce therefrom either aromatic hydrocarbons or other liquid hydrocarbons boiling Within the gasoline range, and for clay treatment and fractionation of the combined gasoline boiling range products to produce a motor fuel of high anti-knock characteristics.

The process provides a flexible means for treating hydrocarbon gases to produce therefrom motor fuel hydrocarbons boiling within the gasoline range. By absorbing the heavier gas constituents in the naphtha which is to be reformed, the necessity for separate conversion of these gases is avoided and at the same time means is provided for charging these gases in the liquid state tol a conversion zone. The light portions of the gases, which cannot be absorbed, can be polymerized separately under conditions which are suitable to the oleiinic content thereof. Moreover, the character of liquid products which may be obtained from the light gases can be regulated at will by independent control of the temperatures and pressures to which they are subjected. If it is not desired to make preponderantly aromatic hydrocarbons, high pressure conditions and lower, temperatures may be used and larger yields of liquid products thereby obtained. Where the primary object is to obtain aromatic hydrocarbons from the light gaseous portions, higher temperatures and lower pressures may be utilized.

By subjecting' the heavier and higher oleiinic gas fraction to conversion absprbed in naphtha, unusually high yields of gasoline of high antiknock value can be obtained. `Apparently polymerization and alkylation take place simultaneously so that saturated as well as unsaturated hydrocarbons take part inthe reaction. The light unabsorbed fraction, on the other hand, is relatively leanv in olefinic content and requires more severe treatment than the absorbed gases. By adjusting the pressure and temperature conditions in absorber I3 in accordance with the composition of the gas fed to it, the gas can be fractionated to yield two fractions most suitable for the particular conditions of reaction to which they are subjected and increased yields thereb obtained.

Although a specific method of cracking, reforming and polymerizing has been shown and described, it is to be understood thaty the invention is not limited to the specific form shown and described, but covers broadly process and apparatus for combining the steps of cracking, reforming and gas polymerization in a unitary process. Furthermore, although the invention has Ibeen described as being applicable to treatment of crude oil, it is apparent that oilnaphtha, and gases from separate sources may be utilized.

What is claimed is:

1. The method for producing motor fuel which comprises contacting low octane naphtha with olefin-containing hydrocarbon gas under conditions of temperature and pressure to absorb heavier constituents of the gas, subjecting the enriched naphtha in a heating and reaction zone .to conditions of temperature and pressure suitable for increasing the octane rating of the naphtha and for converting a portion of the absorbed gas to hydrocarbons boiling within the motor fuel range, conducting gas not absorbed by the naphtha to heating and reaction zones entirely separate from said first mentioned heating and reaction zone and subjecting it to temperatures and under pressures suitable for converting a portion thereof to hydrocarbons boiling within the gasoline range, separating the gasoline boiling constituents from the gas conversion operation from the gases, combining said constituents with the total products from the enriched naphtha conversion operation, and subjecting the combined products with'out prior fractionation to clay treatment followed by frac--` tionation to produce finished motor fuel.

2. Method in accordance with claim 1 in which theolen-containing gas is produced in an oil cracking operation. Y 3. Method in accordance with claim 1 in which the naphtha is obtained from topping crude oil, and the olefin-containing gas is produced in the cracking of the topped crude.

4. Method in accordance with claim 1 in which the gasoline boiling constituents from the l densing gasoline distillate, separating gases from said distillate, contacting cool naphtha, separated in said topping step, with said gases under conditions of temperature and pressure to dissolve heavier constituents of said gas in said naphtha, subjecting the enriched naphtha to conditions of temperature and pressure suitable for reforming said naphtha and lfor converting a portion of the dissolved gas to hydrocarbons boiling Within the gasoline range, subjecting undissolved gases to separate conditions of temperature and pressure suitable for converting them to hydrocarbons boiling within the gasoline range, separating gasoline hydrocarbons resulting from the latter step from the heavier and lighter reaction products, combining said gasoline hydrocarbons withgasoline distillate from the cracking step, contacting the combined gasoline distillate with hot reaction products issuing from the reforming operation under conditions to chill said reaction products below conversion temperature, contacting the total products from the chilling step with clay under conditions of temperature and pressure to de-gum and de-colorize them, and fractionating the clay treated products to produce finished motor fuel.

6. Method in accordance with claim 5 in which the gases resulting from the separategas conversion step are in part recycled to said naphthagas contacting step.

7. Method in accordance with claim 5 in which the gases'resulting from the naphtha reforming step are charged to the naphtha-gas contacting step.

8. Method in accordance with claim 5 in which liquid hydrocarbons heavier than gasoline, pro..- duced in the reforming and gas conversion operations, are recycled to the cracking unit.

9. The process of producing gasoline which comprises, subjecting low octane naphtha in a heating and reaction zone to conditions of ternperature and pressure suitable for increasing the octane rating thereof, quenching the reaction products by means of cool liquid hydrocarbons to suddenly terminate the reaction, fractionating the quenched products into normally liquid and normally gaseous hydrocarbons, contacting the gaseous hydrocarbons in an absorption zone with naphtha to be reformed, charging the rich naphtha to said heating and reaction zone, charging unabsorbed gases to separate heating and reaction zones wherein said unabsorbed gases are subjected to suitable conditions of temperature and pressure to convert a substantial portion thereof to gasoline boiling hydrocarbons, separating the reaction products into gases, gasoline boiling hydrocarbons and hydrocarbons boiling above the gasoline range, charging said last-mentioned gasoline boiling hydrocarbons to the outlet of the first-mentioned reactive zone as part of the quenching liquid, charging raw cracked gasoline to the outlet of said first-mentioned reaction zone as another portion of the quenching liquid, mixing cracked gases with'said gaseous hydrocarbons prior to charging the latter to the absorption zone, and eliminating reaction gases from saidv separate heating and reaction zones from the system.

10. Apparatus of the character described comprising a heating and reaction coil, means for passing liquid to the inlet of said coil, means for charging liquid to the outlet of said coil, fractionating means connected to the outlet of said coll subsequent to said liquid charging means, means for withdrawing gases from the upper part of said fractionating means, an absorber, means for charging said gases to the lower part of said absorber, means for charging liquid to the upper part of said absorber in contact with said gases, means for passing liquid from the lower part of said absorber to the inlet of said reaction coil, means for passing gases from the upper part of said absorber to a second heating means, a reaction means connected to said heating means, a second fractionating means connected to said reaction means, means for passing liquid products from said second fractionating means to the outlet of the heating and reaction coll, and means for eliminating gases, separated in said second fractionating means, from the system. I`

11. Apparatus in accordance with claim 10 in which a clay tower is connected between the means for charging liquid to the outlet of the coil, and the rst fractionating means.

12. Apparatus in accordance with claim 10 including means for charging liquid to the reaction coil or to the absorber.

PEREY A. MASCHWITZ. 

